Top layer 5 1/2 ounces milk chocolate (dark or white chocolate may be substituted)
Grease a 9-inch square cake pan (glass is best).
Sift the flour into a mixing bowl and rub in the butter with your fingers until the mixture resembles fine bread crumbs. Add the sugar and mix to form a fine dough. Press the dough into the bottom of the prepared pan and prick with a fork. Bake in a preheated 375 degree F oven for 20 minutes, until lightly golden. Set pan on a rack to cool (leave in pan).
To make the middle layer, place the butter, sugar, almond paste and sweetened condensed milk in a nonstick saucepan and cook over gentle heat, stirring constantly until the mixture comes to a boil. Reduce the heat and cook for 4 to 5 minutes (until the caramel is pale gold and thick and is coming away from the sides of the saucepan). Pour over the shortbread and leave to cool.
When the middle layer is cool and firm, melt the chocolate in a double boiler. Spread the melted chocolate over the middle layer, leave to set in a cool place, then cut into squares or fingers to serve.
